The invention relates to a tilting and trimming system for an outboard drive unit of a marine vessel. More particularly, the invention relates to an improved hydraulically operated tilting and trimming system adapted for quick tilting up of the drive unit and slow trimming of the drive unit.
As is well known, a variety of hydraulic systems have been employed for achieving tilt and trim movement of a marine outboard drive unit. These system typically include a reciprocating hydraulic or fluid motor, which is interposed between the transom of the marine vessel and the drive unit for adjusting the tilt and the trim of the outboard drive unit in response to extension and contraction of the fluid motor. The fluid motor is powered by a fluid system that is normally contained within the hull of the marine vessel and may include a reversible electric motor and a reversible fluid pump. In connection with such systems, it is normal practice to include a pressure relief valve or valves in the hydraulic circuitry to the fluid motors so as to relieve pressure in the system and protect the system and drive unit from damage in the event the drive unit collides with a submerged or floating obstacle.
Previous tilt and trim systems have been arranged to provide for both quick tilting movement and slow trimming movement of the drive unit. Some of these systems utilize a manual valve coupled to the gear control mechanism of the drive unit to achieve tilting and trimming by shifting the gears of the drive unit. An example of such a system is set forth in U.S. Pat. No. 3,842,789. Other systems utilize a plurality of pistons and a multitude of valves interconnected within the hydraulic circuitry to achieve tilting and trimming functions. Examples of these systems are set forth in U.S. Pat. No. 3,799,104 and Japanese patent 60-234096.
Unlike previous systems arranged to provide both quick tilting and slow trimming of an outboard drive unit, two embodiments of the invention utilize a magnetically operated selector valve electrically linked to the gear throttle control mechanism and a manual switch for effecting quick tilting up movement and slow trimming movement of the drive unit. A third embodiment of the present invention utilizes a means for controlling the voltage applied to the motor to achieve quick tilting up movement and slow trimming movement instead of a selector valve. Fourth and fifth embodiments of the invention utilize a tilt fluid motor for performing tilting operation and a pair of trim fluid motors for trimming the drive unit. The position of the selector valve is controlled in these embodiments by a gear-throttle control or engine speed, and a manual switch.